Surface acoustic wave (SAW) devices are used in various applications. For example, SAW devices can be used as sensors to measure various parameters, such as pressure, humidity, mass, and temperature, to name a few. Because SAW devices are passively energized, they do not require batteries and they can be easily integrated into a data acquisition system.
Many SAW sensors are configured for wireless operation. In such a case, the SAW sensor can receive high-frequency electromagnetic waves emitted by a radio frequency (RF) transceiver, as well as transmit a response signal back to the transceiver. In a typical sensor, the SAW device is formed on a piezoelectric substrate that is mounted to separate a printed circuit board (PCB) to which an independent antenna is also mounted or otherwise connected.
With conventional wireless SAW sensors, the SAW device must be coupled to the antenna with some form of external interconnect that is soldered or bonded in place. Unfortunately, such external interconnects are vulnerable to damage, particularly in extreme environments, for instance in high-temperature environments.